1. Field of the Invention
The invention relates to a contact switch, more particularly to a microswitch, the assembly of which can be fully automated.
2. Description of the Related Art
Microswitches, or switches in which contact is made or broken by a slight motion, are widely known in the art. An example of such a switch is shown in FIGS. 1 and 2 to comprise a switch casing (a); conductors (b), (e1) and (e2); a movable contact arm (c); a spring member (d); a button member (f); and a lever (g). The conductors (b), (e1) and (e2) are mounted to the casing (a) and have downwardly extending leg portions projecting out of the casing (a). A spring mounting plate member (b7) extends from the leg portion of the conductor (b) inside the casing (a). An upward end flange (b4) extends from one end of the mounting plate member (b7) and is provided with an opening (b5). A spring engaging plate (b1) projects upward from the mounting plate member (b7) and is spaced from the end flange (b4). The spring engaging plate (b1) has a top end portion formed with a notch (b2), and a mounting hole (b3). The rear side of the end flange (b4) is provided with a pair of transversely extending guide grooves (b6) provided on opposite sides of the opening (b5). The movable contact arm (c) has a pair of spaced leg portions (c11) abutting and turnable about the guide grooves (b6) of the end flange (b4). The movable contact arm (c) has an engaging opening (c3). One end (d1) of the spring member (d) is hooked to the spring engaging plate (b1) at the notch (b2) and at the mounting hole (b3). The other end (d2) of the spring member (d) passes through the opening (b5) and is hooked to the movable contact arm (c) at the engaging opening (c3). The conductors (e1) and (e2) have contact portions disposed inside the casing (a) and extending respectively above and below the movable contact arm (c). The button member (f) is in contact with the intermediate portion of the spring member (d). The lever (g) is actuated to push the button member (f) downward to correspondingly actuate the spring member (d) to move the movable contact arm (c) upward from a first position, wherein the movable contact arm (c) is in contact with conductor (e2), to a second position, wherein the movable contact arm (c) is in contact with conductor (e1).
The main disadvantage of the above described microswitch lies in the assembly of the spring member (d) with the spring engaging plate (b1) and the movable contact arm (c). Most of the components of the microswitch can be machine assembled, with the exception of the spring member (d). As discussed earlier, the end (d1) of the spring member (d) is first hooked to the spring engaging plate (b1) at the notch (b2) and at the mounting hole (b3). The other end (d2) of the spring member (d) is then maneuvered through the opening (b5) and is hooked to the movable contact arm (c) at the engaging opening (c3). This procedure cannot be achieved by machines and must therefore be done manually. Because of the small size of the components, manually assembling the spring member (d) is difficult and takes up a lot of time. Production is thus low while labor costs are relatively high.